XPInstall (Cross-Platform Install) is a technology used by the Mozilla Application Suite, SeaMonkey,

Mozilla Firefox Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current and a ...

, Mozilla Thunderbird and other XUL-based applications for installing Mozilla extensions that add functionality to the main application. A XPI (pronounced "zippy" and derived from XPInstall) installer module is a

ZIP Zip, Zips or ZIP may refer to: Common uses * ZIP Code, USPS postal code * Zipper or zip, clothing fastener Science and technology Computing * ZIP (file format), a compressed archive file format ** zip, a command-line program from Info-ZIP * Zi ...

file that contains an install script or a manifest at the root of the file, and a number of data files. In Mozilla, Firefox before 0.7, and before 0.5, the package contained a

JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...

install script (install.js) with some directives for actions to take during an install, including adding files and directories, removing old or obsolete files and directories, executing command line tools, etc. In middle-old Firefox and Thunderbird versions, the install script has been replaced by a chrome manifest and a RDF file (install.rdf). Since Firefox version 45, the only mandatory file is manifest.

json JSON (JavaScript Object Notation, pronounced ; also ) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays (or other ser ...

. Since Firefox 1.0, XPIs from sites other than Mozilla Add-ons are blocked by default. This was an attempt to prevent malicious programs, like

computer virus A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code. If this replication succeeds, the affected areas are then said to be "infected" with a compu ...

es,

Trojans Trojan or Trojans may refer to: * Of or from the ancient city of Troy * Trojan language, the language of the historical Trojans Arts and entertainment Music * ''Les Troyens'' ('The Trojans'), an opera by Berlioz, premiered part 1863, part 1890 ...

and

spyware Spyware (a portmanteau for spying software) is software with malicious behaviour that aims to gather information about a person or organization and send it to another entity in a way that harms the user—for example, by violating their privac ...

, from being installed by novice users. While it is possible to put a site into the whitelist that limits sites which can install XPIs, malicious sites cannot install extensions in the background (without human intervention). This is because a confirmation dialog needs to be answered for every single installation of an extension. However, users are still advised to install extensions from trusted sources only.

Applications with built-in support for XPInstall

Web browsers

* Mozilla Application Suite *

* Flock * SeaMonkey *

Netscape Browser Netscape Browser (or ''Netscape 8'') is the eighth major release of the Netscape series of web browsers, now all discontinued. It was published by AOL, but developed by Mercurial Communications, and originally released for Windows on May 19, 2005 ...

Other applications

Nvu Mozilla Composer is the free and open-source HTML editor and web authoring module of the Mozilla Application Suite (the predecessor to SeaMonkey). It is used to create and to edit web pages, e-mail, and text documents easily. It is compatible w ...

(web authoring application) * Songbird (media player and organiser) *

Mozilla Sunbird Mozilla Sunbird is a discontinued free and open-source, cross-platform calendar application that was developed by the Mozilla Foundation, Sun Microsystems and many volunteers.

* Mozilla Thunderbird *

Google Gears Gears, formerly Google Gears, is discontinued utility software offered by Google to create more powerful web apps by adding offline storage and other additional features to web browsers. Released under the BSD license, Gears is free and open-sour ...

External links

* * * {{DEFAULTSORT:Xpinstall Mozilla